Sliding bearing composite materials consisting of a load bearing substrate and a friction reducing layer overlay are generally known.
Sliding bearing composite materials can be used to form a variety of bearings, such as plain bearing bushing used, for example, by the automotive industry. Such plain bearing bushings can be used for door, hood, and engine compartment hinges, seats, steering columns, flywheels, balancer shaft bearings, etc. Additionally, plain bearing bushings formed from the sliding bearing composite materials can also be used in non-automotive applications.
One method of enhancing the adhesion between a load bearing substrate and the friction reducing layer is to apply a surface treatment to the load bearing substrate, such as chromate or a chromic acid treated phosphate. However, surface treatment can include the use of toxic compounds such as hexavalent chromium. Thus, there is an ongoing need for improved bearings that do not rely upon surface treatments such as chromate.